REVIEWS 453 



the base of the Lake Superior sandstone, are placed in the Upper 

 Menominee series. These occur in two great series, the Vulcan and 

 the Hanbury. 



The Vulcan formation is unconformable above the upper part of 

 the Lower Huronian, which for most of the district is the Randville 

 formation, and unconformable below the Hanbury slate. For parts of 

 the district the Vulcan iron-bearing formation does not appear at all 

 between the dolomite and the slate and its absence is explained by the 

 unconformity between the Vulcan formation and the Hanbury slate. 

 The Vulcan formation embraces three members. These are, from the 

 base up, the Traders iron-bearing member, the Brier slate, and the 

 Curry iron-bearing member. They are mapped as a single formation. 

 The principal area of the Vulcan iron formation is in the belt 900 to 

 1300 feet wide, following the sinuosities of the southern border of the 

 southern belt of Randville dolomite. It is generally absent north of 

 the southern belt except at the east end where it appears at the Loretto 

 mine and eastward. The second important area of Vulcan iron for- 

 mation stretches off about five miles along the south side of the central 

 dolomite belt running north of Lakes Antoine and Fumee, and ending 

 somewhere about the east line of Range 30 West. At the east end of 

 the dolomite area the iron-bearing formation appears in the lean slates 

 at Iron Hill. The third stretch of country in which the iron-bearing 

 beds are to be expected is that which borders the northern dolomite 

 belt, but while pits have shown the existence of the formation here its 

 distribution is unknown. The other areas in which the Vulcan for- 

 mation may occur are those bordering the Quinnesec schists, but this 

 has not yet been determined. 



The Traders member consists of ferruginous conglomerate, ferru- 

 ginous quartzite, heavily ferruginous quartzose slates and iron ore 

 deposits. The Brier member consists of heavy black ferruginous and 

 quartzose slates. The Curry member consists of interbedded japsilite, 

 ferruginous quartzose slates and iron ore deposits. The relations of 

 the Traders and Brier Hill members where there has been no disturb- 

 ance of the strata is that of gradation. Where there has been disturb- 

 ance, as in the vicinity of Norway, there has been a zone of differential 

 movement between the two, resulting in slickensides and brecciated 

 zones. Between the Brier slates and the Curry member there is gra- 

 dation. 



The Vulcan formation is bent into folds of several orders of 



